^■^»»1 . BOTANICAL SYSTEMS. 437 



The following table may be taken to represent, so far as the tabular 

 form will permit, the system of classification called for by the present 

 known facts of structural botany and of paleontology. 



Assumed natural system. 

 Cryptogams. 



' ( Oycadaceae. 



Gymnosperms. } Coniferse. 



Phsenogams. 



Gnetaceae. 

 C Monocotyledons. 



^Si««P«^°^«--] Dicotyledons JpJlypefal^. 

 (^ ( Gamopetalse. 



A glance at this table will show that the most important respect in 

 which it differs from the one last examined is in the position and rank 

 of the Gymnosperms. Whereas there the Gymnosperms and Angio- 

 sperms have only the rank of subclasses under the class Exogens, or 

 Dicotyledons, they here assume the rank of classes, and the Monocotyle- 

 dons and Dicotyledons are reduced to subclasses under the class An- 

 giosperms. The Gymnosperms are thus taken out of the Dicotyledons 

 entirely. This is done because the distinction of open and closed ovaries 

 is regarded as a class distinction, and the Monocotyledons are as truly 

 Angiospermsas are the Dicotyledons, since they possess the closed ovary; 

 because the Gymnosperms are not dicotyledonous, the number of cotyle- 

 dons varying from one to fifteen ; and because, while all Gymnosperms 

 are not strictly exogenous nor all Monocotyledons strictly endogenous, 

 the woody structure of the Coniferse differs fundamentally from that of 

 all dicotyledonous plants. But a discussion of these points would carry 

 us too far. 



It will also be perceived that the order proposed by Adrien de Jus- 

 sieu for the divisions of the Dicotyledons is here adopted, the reasons 

 for which have already been referred to and will receive more special 

 attention hereafter. 



6. CLASSIFICATION OF THE CRYPTOGAMS. 



Thus far we have considered the Cryptogams as an undivided group 

 of plants ; but they too are capable of subdivision. The classification 

 of the Cryptogams, however, is still in its infantile stage and is the 

 problem which is at this moment most earnestly claiming the attention 

 of advanced botanists. The subject is too special to be entered into 

 here, and I shall confine myself to naming a few of the groups which 

 modern investigation has shown to throw some light upon the more 

 general problem of descent in plant life. 



That the first proper plants were cellular Cryptogams there is no 

 question, and to that class still belong a great number and variety of 

 forms, the seaweeds, fresh- water algse, fungi, lichens, liverworts, mosses, 

 etc. Prom these have in all probability descended the vascular Crypto- 



